While the invention is subject to a wide range of applications, it is especially suited for use as an apparatus and method for making dry cells and will be particularly described in that connection.
In producing dry cell batteries of substantially uniform performance characteristics and of a uniform quality, it is necessary to place a uniform quantity of depolarizing mix in each cell can and to compact the mix uniformly. It is also desirable to discharge most of the air from the can so that it will not create internal resistance in the cell can.
The general technique of constructing a dry cell battery follows. A paper liner is formed and inserted into a cell can. Next a paper washer is inserted into the can. This washer is initially positioned in the can near its upper opened end. The side walls of the cup-shaped washer have sufficient inherent elasticity to force the paper liner into close proximity with the inner wall of the can as the washer is moved downward into the can. After the washer is placed into the can, the can is advanced over an extruder nozzle until the end of the nozzle reaches nearly to the bottom of the can. This movement pushes the washer to the bottom of the can as explained in U.S. Pat. No. 3,198,221 to Orlando. The nozzle delivers into the can, by way of example, a depolarizing mix of manganese dioxide, conductive carbon, suitable electrolyte salts, such as ammonium chloride and zinc chloride and enough water to make a pasty mass as required.
The extruder nozzle is formed of a relatively thin walled tube with an outside diameter nearly the same as the internal diameter of the can. The can is supported by a spring biased support device which allows the can to move off the nozzle against the force of the spring as the depolarizing mix enters into the can.
More specifically, when the pressure created by the depolarizing mix being delivered to the can reaches the spring pressure, the can moves back off the nozzle as further mix enters the can. Means are provided so that the can stops moving just before the last of the mix is delivered to the can. The last of the mix, delivered to the can after its movement has been arrested, causes a consolidation of the material in the can to a desired pressure and predetermined height.
In using the extruder as described in the previously mentioned patent, the spring of the support device is set to achieve good consolidation of the mix as the latter entered the can. The amount of consolidation is very important. If a very tight consolidation is attempted at the extruder, it often leads to a build up of the material around the sides of the extruder nozzle and generally messy operation. On the other hand, if there is little or no consolidation, the slug of mix will not adequately wet the paper liner.
Thus, the goal or optimum condition is where the mix is consolidated without squeezing excess liquid out of the mix to overly wet the paper liner and paper washer and produce cells of inconsistent quality and varying amperage.
The cell is next moved to a station downstream from the extruder where a cardboard mix washer is inserted to very loosely bear against the mix. The cell is then moved to the next station were a carbon rod is driven through the mix washer into the depolarizing mix. The rod displaces a portion of the mix and forces it outward towards the sides of the can and upward against the mix washer. The battery continues to move downstream and is completed, as explained below. In some instances, the washer is loose after this operation, and/or the mix is not properly consolidated. The result is batteries with varying operational characteristics and amperages.
It is an object of the present invention to provide an apparatus and method for delivering depolarizing mix into a dry cell can in a manner to substantially obviate one or more of the limitations and disadvantages of the described prior arrangements.
It is a further object of the present invention to provide a method and apparatus for delivering depolarizing mix into a dry cell can whereby uniform consolidation of the mix can be achieved in substantially every battery.
It is a further object of the present invention to provide a method and apparatus for delivering depolarizing mix into a dry cell can whereby a mix washer is used to consolidate the depolarizing mix.